1. Field of the Invention
The present invention relates to a method for eliminating the stringent taste and alleviating stringent feeling in the stomach of L-arginine (hereinafter referred to as arginine) by mixing L-ascorbic acid (hereinafter referred to as ascorbic acid) and for alleviating the toxicity of arginine-derived NO radical by arginine-ascorbic acid-combined treatment.
2. Description of the Related Art
From late 1970's to 1980's, a research group of Illinois University reevaluated that dietary arginine is indispensable for optimal health of adult and especially aged humans. (see E. Kimoto, “Nutritional Chemistry of L-Arginine”, Kaisei Publishing Co. Ltd., Tokyo, 1999 (Literature 2), page 93).
In 1987, it was reported that NO radical participating in a wide variety of physiological functions such as blood pressure control and prevention of infections is derived from arginine as a source. This led to increased attention paid to arginine in the field of amino acid nutrition science (see Literature 2, page 57).
Arginine participates in assorted physiological functions. For example, it stimulates detoxication of ammonia via urea cycle, serves as material for the synthesis of creatine phosphate (bioenergy storing form), polyamine (bioactive substance) and proline (an amino acid constituent of collagen), stimulates secretion of endocrine hormones, serves as a source for the production of NO radicals (inter/intra cellular signal transducer) and so forth.
Concerning the nutritional and metabolic aspects of basic amino acids, overabundance of lysine (one of the essential amino acids) and insufficiency of arginine, that is, imbalance of lysine/arginine ratio inhibits antagonistically many of metabolic pathways of arginine, thus can be harmful to health (see Literature 2, page 76).
Furthermore, arginine has been increasingly appreciated not only as a nutrient for average people as collective but also as a “conditionally indispensable” nutrient in order to maintain better health conditions of individuals suffering from some complaint or diseases.
In particular, arginine is an indispensable nutrient for the therapy of post-operative stress or invasion (see Literature 2, page 93).
As described above, alimentation or supplement of arginine is a very useful method for maintaining health. However, arginine and its salt of inorganic acid, such as hydrochloric acid, nitric acid or sulfuric acid have a very stringent taste (harsh, acrid taste, irritating the throat), so that it is very difficult for people to take arginine or the salt. Furthermore, after the intake of arginine or the salt, it often causes stringent feeling in the stomach (heartburn, nausea or vomiting) so that it makes the intake of arginine unpleasant.
Long-term intake of arginine results in increased production of NO gas which changes easily into nitrous acid. A portion of the nitrous acid reacts with dietary-intaken secondary amines to produce carcinogenic nitrosamine compounds. It is well known that ascorbic acid as an antimutagenic vitamin inhibits such a harmful reaction (see, the lower part in the page 10 of Literature 1).
Active oxygen species such as superoxide radical anion (O2·−) are often produced in diseased cells. NO radical readily reacts with O2·− and produces deleterious peroxynitrite (O═NOO−) (see, the middle part in the page 64 of Literature 2).